Caterpillar 378-6178 Radiator

Fitment and Service Notes

The 320D family is the highest-volume excavator line on the used market across Africa, the Middle East and Latin America, and its cooling package changed several times in production. The part-number chain runs 312-8338 → 481-3475 → 265-3624 → 265-3625, with later builds more commonly quoted as 326-3870, and 378-6178 is the water tank radiator number listed across the 320C, 320D and 323D — covering the 3066-engined 320C generation through the C6.4-engined D-series builds (checked against aftermarket listings, August 2026). So if your machine is an early 320C or a D-series unit, 378-6178 is one of the numbers in play — but the model name alone is not enough.

The reliable path is the same as with every Cat cooling part: your machine serial number plus photos of the old unit, so we can compare core height, tank shape and bracket positions. If the old radiator still carries a legible number, send it — we cross-reference it directly. For the later 320D-family builds the equivalent page is the Cat 320D radiator 326-3870; the early-to-mid D-series number is 265-3625, and the bigger 330D/336D class (C9 engine) uses 245-9359.

Plan your order around the whole cooling package, not just the radiator: on the Komatsu side the PC200-8 radiator 20Y-03-41651 and its intercooler 20Y-03-41131 (listed at about $715, August 2026) sit in the same stack logic, and a worn fan clutch will damage a new radiator exactly as it damaged the old one. Typical aftermarket pricing for this size class runs roughly $250–600, against an OEM price in the $900–1,800 territory — quality aftermarket parts are cross-referenced to the OEM number at 30–60% below OEM list. For the broader picture — part numbers across the Cat lineup, failure signs and replacement logic — see our Caterpillar radiator guide, the heavy equipment cooling system parts guide and the radiator replacement guide.

FAQ

Q: Does the 378-6178 radiator fit my Cat 320D?
A: 378-6178 is a water tank radiator listed for the 320C, 320D and 323D excavators, spanning the 3066-engined 320C through the C6.4-engined 320D/323D builds (checked August 2026). Within the 320D family it sits alongside 265-3625 and the later 326-3870 — send your serial and photos and we confirm the exact unit for your build before dispatch.

Q: Is this radiator OEM or aftermarket?
A: This is a high-quality aftermarket radiator cross-referenced to OEM 378-6178, typically priced 30–60% below OEM list. The OEM cross-reference is written on the order and fitment is confirmed by serial number before shipping.

Q: What does a Cat 320D radiator cost?
A: For the 20-ton class, aftermarket radiators run roughly $250–600 against $900–1,800 OEM (checked August 2026); the later 320D-family number 326-3870 lists from about $90–500 on Amazon. We quote on your serial-confirmed fitment, FOB Shanghai or CIF to your port.

Q: How do I order this radiator from CN Machinery?
A: Message us on WhatsApp or email sales@cn-machinery.com with your machine serial number and photos of the old radiator. Stock items dispatch in 3–7 days, FOB Shanghai or CIF to your port, with payment by T/T.